Aprons, when to use them and when not to use them

Aprons are shown on a lot of period pictures, both on men and women. I'm talking the period around 1400 here.
The men wearing aprons are often smiths, butchers and other with a messy business.
The women with aprons are often working with cooking, baking and the like, also potentionally messy business. Women not working, but taking part in a feast, visiting, walking the street, normally don't wear an apron. Very fine women normally don't war aprons.
Looking at reenactors, many women seem to keep on their apron at all times, as if it were a set part of the dress, like you see it in the 16th century.
Also there is a tendency to wear the belt over the apron, showing a bunch of kees, poutch, knife and other stuff hanging in the belt, something I can't remember having seen in period pictures.
Summa summarum: think about what you are doing and put an apron when cooking, tending the fire, spinning etc, and put it over your belt, but take it of when leaving your house, going shopping at the market,  visiting or the like.

Wife spinning, she's wearing an apron to protect her dress.

Some online aticles and references:
http://rosaliegilbert.com/aprons.html
http://www.larsdatter.com/aprons.htm
http://www.acmeaprons.com/history-of-aprons.html